Hello,

when I write a mail to the address uwe@kleine-könig.de if finds its way
to the right server ("Received: ... for <uwe@xn--kleine-knig-yfb.de>
...."), but the To: header looks wrong. Icedove writes

	To: uwe@kleine-könig.de

in utf-8 (that is, the ö as the two-byte sequence 0xc3 0xb6) without any
further quoting. I think this violates the respective RFCs.
The same happens when I use this address as sender address.

When this mail is shown in icedove, it displays the To: header as:

	To: uwe@kleine-k�nig.de

(i.e. with the three-byte sequence 0xef 0xbf 0xbd). AFAICT the broken
display is OK, because after all the mail is broken.

When sending a mail with Mutt to this idn-address it correctly encodes
to xn--kleine-knig-yfb.de in the To: header which icedove shows as is
after receipt.
(While mutt displays this as "To: uwe@kleine-könig.de".)

Best regards
Uwe